JP5697725B2 - Display device, display control method, and electronic device - Google Patents

Description

  The present invention relates to a display device for displaying a predetermined video, a display control method for controlling the display device, and an electronic apparatus using the display device.

  Conventionally, the following is used for a photosensor used for light control of a liquid crystal display device. That is, in the case of a liquid crystal display device using an amorphous silicon TFT, as shown in FIG. 21, a constant current circuit is connected to the sensor output, and the photocurrent is detected by converting the current into a voltage.

  In addition, since low temperature polysilicon (hereinafter referred to as “LTPS”) can form a circuit on a substrate, a circuit configuration in which a comparator is connected to the sensor output as shown in FIGS. 22 and 23 is also possible. Since the circuit area can be reduced, it can be arranged around the pixel.

JP 2007-018458 A

However, when a photosensor is applied to a display device using LTPS, there are the following problems.
Problem (a): The leak amount (dark current) of the photosensor (transistor) is larger than that of single crystal silicon.
Problem (b): The light leak amount (bright current) of the photosensor is small.
Problem (c): There are large variations in performance (individual differences) of elements such as photosensors and comparators in the same liquid crystal display device (panel).
Problem (d): There is a temperature change in the dark current of the photosensor.
Unless the above factors are solved, it is difficult to produce a photosensor with high accuracy in a liquid crystal display device using LTPS.

  The present invention has been made to solve such problems. That is, according to the present invention, any one of a first detection element that detects the amount of external light, a second detection element that detects a dark current during light shielding, and the first detection element and the second detection element. A selection means for selecting one; a comparator for comparing the output of the first detection element or the second detection element selected by the selection means with a predetermined reference value; and the first detection element by the selection means. The difference between the first comparison result by the comparator when selected and the second comparison result by the comparator when the second detection element is selected is calculated, and the display area is displayed according to the calculation result. And a control unit that controls the amount of light to be applied.

  In the present invention as described above, the output of the first detection element that detects the amount of external light and a predetermined reference value are compared, and the output of the second detection element that detects the dark current during light shielding and the predetermined reference. Since the comparison with the value is performed by one comparator, it is possible to eliminate the influence due to the performance variation of the comparator.

  In the present invention, since two comparison results are obtained by one comparator, the first detection element or the second detection element is selected by the selection means, and two comparison results can be obtained by time division. Become.

  Further, both detections are performed by switching between a predetermined reference value when the output of the first detection element is compared with the comparator and a predetermined reference value when the output of the second detection element is compared with the comparator. It is possible to suppress errors in the calculation results due to variations in element performance.

  Further, the amount of external light can be switched by switching the additional capacitor commonly connected to both the detection means when the selection means selects the first detection element and when the second detection element is selected. It is possible to adjust the detection time of both detection elements when detecting the dark current and when detecting the dark current.

  Here, the detection element is an element that can output a current corresponding to the amount of received light, and includes a diode configuration and a transistor configuration.

  In addition, the present invention provides a display control method for a display device including a first detection element that detects the amount of external light and a second detection element that detects a dark current during light shielding. A step of detecting a dark current at the time of light shielding and calculating a comparison value at the time of light shielding by comparison with a predetermined reference value; a current corresponding to the amount of light in the vicinity by the first detection element; A step of calculating a comparison result at the time of light reception by comparing the two, a step of calculating a difference between the comparison result at the time of light reception and a comparison result at the time of light shielding, and controlling a light amount applied to the display area according to the calculation result This is a display control method.

  In the present invention as described above, the output of the first detection element that detects the amount of external light and a predetermined reference value are compared, and the output of the second detection element that detects the dark current during light shielding and the predetermined reference. When the comparison with the value is performed by one comparator, the comparison by the first detection element and the comparison by the second detection element are switched, so that the influence due to the performance variation of the comparator can be eliminated. .

  In addition, according to the present invention, in an electronic device in which a display device is provided in a housing, the display device detects a first detection element that detects the amount of external light, and a second detection element that detects a dark current when light is blocked. Selection means for selecting one of the first detection element and the second detection element, the output of the first detection element or the second detection element selected by the selection means, and a predetermined reference value A first comparison result by the comparator when the first detection element is selected by the selection means, and a second comparison by the comparator when the second detection element is selected Control means for calculating a difference from the result and controlling the amount of light applied to the display area according to the calculation result.

  In the present invention as described above, the output of the first detection element that detects the amount of external light and a predetermined reference value are compared, and the output of the second detection element that detects the dark current during light shielding and the predetermined reference. Since the comparison with the value is performed by one comparator, the influence due to the performance variation of the comparator can be eliminated, and the amount of light applied to the display area can be controlled with high accuracy.

  The present invention has the following effects. That is, when a photosensor is applied to a display device using LTPS, it is possible to accurately adjust the amount of light applied to the display region while suppressing the influence of detection errors due to performance variations of each element.

It is a schematic block diagram of the display apparatus which concerns on this embodiment. It is a schematic block diagram of the other display apparatus which concerns on this embodiment. It is a circuit diagram explaining the principal part of the display apparatus which concerns on 1st Embodiment. It is a circuit diagram explaining the principal part of the display apparatus which concerns on 2nd Embodiment. It is a circuit diagram which shows the structure which can change the element size of a 2nd photosensor. It is a figure which shows the temperature characteristic of dark current. It is a figure explaining the flow of the display control method which concerns on 3rd Embodiment. It is a figure which shows the timing of the image display to a display area, and the detection by a photo sensor. It is a figure explaining the operation | movement timing of an initialization period. It is a schematic diagram which shows the example of a flat type module shape. It is a perspective view which shows the television with which this embodiment is applied. It is a perspective view which shows the digital camera to which this embodiment is applied. It is a perspective view which shows the notebook type personal computer to which this embodiment is applied. It is a perspective view which shows the video camera to which this embodiment is applied. It is a figure which shows the portable terminal device to which this embodiment is applied, for example, a mobile telephone. It is a block diagram showing the structure of the display imaging device which concerns on the 1st Embodiment of this invention. FIG. 2 is a block diagram illustrating a configuration example of an I / O display panel illustrated in FIG. 1. It is a circuit diagram showing the structural example of each pixel. It is a circuit diagram for demonstrating the connection relation of each pixel and the sensor reading H driver. It is a timing diagram for demonstrating the relationship between the ON / OFF state of a backlight, and a display state. It is FIG. (1) explaining a prior art example. It is FIG. (2) explaining a prior art example. It is FIG. (3) explaining a prior art example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Outline of display device>
FIG. 1 is a schematic configuration diagram of a display device according to the present embodiment. That is, the display panel 10 which is the display device of the present embodiment scans a display area (sensor area) 11, a selection switch 12 that performs scanning in the display H (horizontal) direction, and a display V (vertical) direction. A V driver 13, a display driver 14, a sensor driver 15, and a plurality of photosensors PS are provided.

  The display area (sensor area) 11 emits display light by modulating light from a backlight (not shown). The plurality of photosensors PS are arranged around the display area 11 and are driven by the sensor driver 15. The display driver 14 and the sensor driver 15 are integrated circuits and are mounted on the substrate as chip components.

  The selection switch 12 line-sequentially drives the liquid crystal elements of each pixel in the display area 11 together with the V driver 13 based on a display driving display signal and a control clock supplied from the display driver 14.

  A plurality of photosensors PS are arranged around the display area 11. The photosensor PS has a diode configuration or a transistor configuration, and is formed on the same substrate as the drive element formed in the display area 11, for example.

  The display panel 10 is connected to an external interface (for example, a display interface and a CPU interface) and a backlight controller by a cable, and is driven by a control signal and a video signal from these.

  In the example shown in FIG. 1, four photosensors PS are provided corresponding to the corners of the display area 11, but it is sufficient that at least two photosensors are provided. The first photosensor to detect is the second photosensor that detects the dark current when light is blocked. In the present embodiment, the control unit (backlight controller) controls the amount of light of the backlight based on the detection results by these photosensors.

  FIG. 2 is a schematic configuration diagram of another display device according to the present embodiment. The display panel 10 that is the display device shown in FIG. 2 is the same as the display panel 10 shown in FIG. 1 described above except that the arrangement of the photosensors PS is different. That is, in the display panel 10 shown in FIG. 2, the photosensor PS is arranged in the display area 11, and the amount of external light is detected by the photosensor PS arranged in the display area 11.

  In the example shown in FIG. 2, four photosensors PS in the display area 11 are provided, but it is sufficient that at least two photosensors are provided. Among them, one photo sensor PS is arranged in the display area 11, and the other one photo sensor PS is provided in the display area 11 or around the display area 11.

  Here, the photo sensor PS arranged in the display area 11 is a first photo sensor that detects the amount of external light, and other photo sensors PS provided in the display area 11 or around the display area 11 are shielded from light. The second photosensor detects the dark current. In the present embodiment, the control unit (backlight controller) controls the amount of light of the backlight based on the detection results by these photosensors.

  Next, a specific application example of the two photosensors in the display device will be described.

<First Embodiment: Configuration for Eliminating Effects of Individual Differences in Comparator Characteristics>
The present embodiment is a photosensor formed on the same substrate in the vicinity of the display area or in the display area, the first photosensor for detecting the amount of external light and the second for detecting the dark current during light shielding. In the configuration for calculating the output from the photosensor, the first photosensor and the second photosensor are switched and the detection result is held using the same comparator (comparator). The circuit configuration is to obtain the difference between the two.

  Here, in the conventional example shown in FIG. 23, the dark current is automatically removed. However, when the method of FIG. 22 is used, it is necessary to remove the dark current on the output side. In order to remove the dark current, two photosensors are arranged, and one side of the sensor is shielded by a color filter (Black) so that light does not strike. Since the output of the shielded sensor is only for the dark current, it is possible to calculate only the bright current by calculating the difference from the output of the sensor to which the light is applied.

  However, when the conventional structure is realized by LTPS, there is a problem in that the comparator has a large individual difference, resulting in a difference in output.

  Therefore, in the present embodiment, as shown in FIG. 3, the switches SW1 and SW2 are attached to the outputs of the photosensors PS1 and PS2 on the light control side and the light shielding side, respectively, and readout is performed in a time-sharing manner using the same comparator 102. Thus, the error of the comparator 102 can be removed, and further, the effect of reducing the circuit area can be obtained.

<Display Control Method by Display Device According to First Embodiment>
As described above, the display device according to the present embodiment is provided with the first photosensor PS1 that detects the amount of external light and the second photosensor PS2 that detects the dark current during light shielding. In this configuration, a single comparator 102 compares these detection results with a predetermined reference value. Therefore, the first photosensor PS1 and the second photosensor PS2 are switched, and the comparator 102 is operated in a time division manner.

  First, the changeover switch SW1 of the first photosensor PS1 is turned off, and the changeover switch SW2 of the second photosensor PS2 is turned on. In this state, the reset of the second photosensor PS2 is turned ON / OFF once to start detection. Since the second photosensor PS2 is provided with a black color filter, dark current is measured when light is blocked. The detection result is sent to one input of the comparator 102. In addition, a predetermined reference value used when the second photosensor PS2 is selected is input to the other input of the comparator 102.

  Then, the time (for example, the number of steps) from the start of detection until the detection value of the second photosensor PS2 exceeds a predetermined reference value is counted and stored in the memory of the difference calculation circuit 104.

  Next, the changeover switch SW2 of the second photosensor PS2 is turned off, and the changeover switch SW1 of the first photosensor PS1 is turned on. In this state, the reset of the first photosensor PS1 is turned ON / OFF once to start detection. The first photosensor PS1 can receive ambient light and measures the current during bright light. The detection result is sent to one input of the comparator 102. In addition, a predetermined reference value used when the first photosensor PS1 is selected is input to the other input of the comparator 102.

  Then, the time (for example, the number of steps) from the start of detection until the detection value of the first photosensor PS1 exceeds a predetermined reference value is counted and stored in the memory of the difference calculation circuit 104.

  Next, the detection result of the first photosensor PS1 and the detection result of the second photosensor PS2 stored in the memory of the difference calculation circuit 104 are read, and the first photosensor PS1 is read by the difference calculation circuit 104. The calculation result is subtracted from the detection result of the second photosensor PS2. As a result, a result obtained by subtracting the dark current from the detection result at the time of bright light can be obtained. And based on this calculation result, the light quantity of the backlight irradiated to the display area 11 (refer FIG. 1) is controlled by a backlight controller. For example, the light amount of the backlight is increased as the peripheral light amount is increased, and the backlight light amount is decreased as the ambient light amount is decreased.

In this way, the detection results for the two photosensors PS1 and PS2 are compared by one comparator 102, and the calculation is performed using the values. Therefore, the influence due to the characteristic variation of the comparator 102 can be reduced , and the accurate It is possible to detect the amount of light.

<Second Embodiment: Configuration for Eliminating Effects of Individual Differences in Photosensor Characteristics>
FIG. 4 is a circuit diagram illustrating a main part of the display device according to the second embodiment. This display device switches between a first photosensor PS1 that detects the amount of external light, a second photosensor PS2 that detects dark current when light is blocked, and a first photosensor PS1 and a second photosensor PS2. Although it is the same as that of 1st Embodiment (refer FIG. 3) by the point provided with changeover switch SW1, SW2, and the comparator 102, it is connected to the output line common to 1st photosensor PS1 and 2nd photosensor PS2. The difference is that the additional capacitor C is variable and the reference value of the comparator 102 is variable.

  The additional capacitor C in the display device of the present embodiment can be switched between when the first photosensor PS1 is selected and when the second photosensor PS2 is selected. Further, the reference value of the comparator 102 in the display device of the present embodiment can be switched between the case where the first photosensor PS1 is selected and the case where the second photosensor PS2 is selected.

  Here, when the light quantity is detected by the first photosensor PS1 and the second photosensor PS2, if there are individual differences in element characteristics between the first photosensor PS1 and the second photosensor PS2, This will cause the accuracy of the output to decrease.

  Therefore, in the present embodiment, as a means for adjusting the individual difference between the elements of the photosensors PS1 and PS2, a configuration capable of changing the additional capacitor C and changing the reference value of the comparator 102 as described above is adopted. .

  In such a configuration, the individual calibration of the elements of the photosensors PS1 and PS2 can be absorbed by performing initial calibration for the display device and feeding back the value. For example, in initial calibration (for example, calibration at the time of product shipment), detection results when dark current is detected by the first photosensor PS1, and detection when dark current is detected by the second photosensor PS2. The additional capacity C or the reference value is adjusted so that the result matches.

  Specifically, when adjusting the additional capacitance C, first, the reference value of the comparator 102 is set to be constant ref1, and the first photosensor PS1 sets the constant additional capacitance C (referred to herein as C1). In this case, the dark current is detected, and the comparison result by the comparator 102 is obtained.

  Next, the dark current is detected by the second photosensor PS2 using the same reference value ref1 of the comparator 102 as before, and the comparison result by the comparator 102 is obtained. At this time, the additional capacitor C is varied to determine an additional capacitor C (referred to herein as C2) that matches the previously detected comparison result of the first photosensor PS1.

  When adjusting the reference value, first, the additional capacitor C is fixed to C1, and the reference value of the comparator 102 is set to be constant ref1. Then, the dark current is detected by the first photosensor PS1, and the comparison result by the comparator 102 is obtained. Next, a dark current is detected by the second photosensor PS2 in the same additional capacitor C1 as before, and a comparison result by the comparator 102 is obtained. At this time, the reference value of the comparator 102 is changed to determine a reference value (referred to herein as ref2) that matches the previously detected comparison result of the first photosensor PS1.

  Then, the additional capacitance C1 or reference value ref1 corresponding to the first photosensor PS1 and the additional capacitance C2 or reference value ref2 corresponding to the second photosensor PS2 are stored in the actual light quantity measurement. Apply.

<Display Control Method by Display Device According to Second Embodiment>
As described above, the display device according to the present embodiment is provided with the first photosensor PS1 that detects the amount of external light and the second photosensor PS2 that detects the dark current during light shielding. In this configuration, a single comparator 102 compares these detection results with a predetermined reference value. For this reason, the first photosensor PS1 and the second photosensor PS2 are switched by the changeover switches SW1 and SW2, and the comparator 102 is operated in a time division manner. Further, on the premise that the additional capacitance C1 or reference value ref1 corresponding to the first photosensor PS1 and the additional capacitance C2 or reference value ref2 corresponding to the second photosensor PS2 are stored in advance. Switch to and measure.

  First, the changeover switch SW1 of the first photosensor PS1 is turned off, and the changeover switch SW2 of the second photosensor PS2 is turned on. Further, the additional capacitor C2 or the reference value ref2 corresponding to the second photosensor PS2 stored in advance is set, and in this state, the reset of the second photosensor PS2 is turned ON / OFF once and the detection is started. To do. Since the second photosensor PS2 is provided with a black color filter, dark current is measured when light is blocked. The detection result is sent to one input of the comparator 102. A predetermined reference value ref2 used when the second photosensor PS2 is selected is input to the other input of the comparator 102.

  Then, the time (for example, the number of steps) from the start of detection until the detection value of the second photosensor exceeds a predetermined reference value ref2 is counted and stored in the memory of the difference calculation circuit 104.

  Next, the changeover switch SW2 of the second photosensor PS2 is turned off, and the changeover switch SW1 of the first photosensor PS1 is turned on. In addition, an additional capacitor C1 or a reference value ref1 corresponding to the first photosensor PS1 stored in advance is set, and in this state, the reset of the first photosensor PS1 is turned ON / OFF once to start detection. To do. The first photosensor PS1 can receive ambient light and measures the current during bright light. The detection result is sent to one input of the comparator 102. Further, a predetermined reference value ref1 used when the first photosensor PS1 is selected is input to the other input of the comparator 102.

  Then, the time (for example, the number of steps) from the start of detection until the detection value of the first photosensor PS1 exceeds a predetermined reference value ref1 is counted and stored in the memory of the difference calculation circuit 104.

  Next, the detection result of the first photosensor PS1 and the detection result of the second photosensor PS2 stored in the memory of the difference calculation circuit 104 are read, and the first calculation is performed by the difference calculation circuit 104 (see FIG. 3). The calculation result of subtracting the detection result of the second photosensor PS2 from the detection result of the photosensor PS1 is performed. As a result, a result obtained by subtracting the dark current from the detection result at the time of bright light can be obtained. And based on this calculation result, the light quantity of the backlight irradiated to the display area 11 (refer FIG. 1) is controlled by a backlight controller. For example, the amount of backlight increases as the amount of external light increases, and the amount of backlight decreases as the amount of external light decreases.

As described above, the two photosensors PS1 and PS2 are detected by setting the additional capacitors C1 and C2 or the reference values ref1 and ref2, respectively, and the detection results are compared by one comparator 102. Sensors PS1 and PS2 can reduce the influence of the characteristic variation and the characteristic variation of the comparator 102, so that accurate light quantity detection can be performed.

  In addition to the switching of the additional capacitance C or the reference value as described above, the following can be considered as a configuration for suppressing the characteristic variation between the two photosensors PS1 and PS2.

(1) It has a function of changing the element sizes of two photosensors (or one of them) and incorporates a circuit that can control the element sizes of these photosensors from the outside. FIG. 5 is a circuit diagram illustrating a configuration in which the element size of the second photosensor can be changed. A plurality of second photosensors PS2 are provided in parallel, and how many of these are provided can be selected by a switch. This selection is obtained in advance by initial calibration, and is applied when detecting the amount of light (dark current) using the second photosensor PS2. The element size to be selected may be set to a value recorded in advance in the nonvolatile memory. Further, a fuse may be provided instead of the switch, and the fuse may be burned out according to the element size to be selected.
(2) A photosensor formed on the same substrate as the display area, wherein the power supply voltage of the photosensor element can be changed in accordance with the element characteristics of the photosensor.
(3) A function is provided for varying the voltage applied to the photosensor when two photosensors (or one of them) are reset, and a circuit that can control the voltage applied to the photosensor from the outside is incorporated. A voltage to be applied at the time of resetting is obtained in advance in the initial calibration, and is applied when detecting the amount of light (dark current) using a photosensor.

<Third Embodiment: Configuration to Avoid Degradation of Resolution due to Temperature and Illuminance of External Light>
The present embodiment is a technique for avoiding a decrease in resolution of the photosensor due to temperature and external light illuminance, using the display device configured as shown in FIGS.

  In LTPS, as shown in FIG. 6, the dark current (transistor leakage) characteristic has a severe temperature characteristic. Therefore, in the configuration of the display device shown in FIG. 4 or FIG. 5, in the case of a sensor circuit that charges the current flowing through the photosensor element to the capacitor and outputs it as time through the comparator, the dark current increases on the high temperature side. Since the electric charge charged in the capacitor increases, there is a problem that the output time is shortened and the detection resolution is lowered.

  Therefore, in the present embodiment, an additional capacitor C that is selectable from the outside and used in the display device shown in FIGS. 4 and 5 is used to avoid a decrease in resolution of the photosensor due to temperature and ambient light illuminance.

  In other words, in a situation where charge is immediately accumulated in the additional capacitor C at a high temperature or high illuminance and the resolution is lowered, the additional capacitor C is increased by external control, and the additional capacitor C is charged. The resolution of the photo sensor is increased by extending the time. Conversely, at low temperatures and low illuminance when the current is low, the additional capacitor C is made small to control the time for charging the additional capacitor C to shorten the measurement time.

  Such switching control of the additional capacitor C is performed in the initialization period before the dark current detection by the second photosensor PS2 and the peripheral light amount detection by the first photosensor PS1 described above. An example of the initialization period is a vertical blanking period when an image is displayed in the display area 11 (see FIG. 1).

<Display Control Method by Display Device According to Third Embodiment>
Next, a specific display control method by the display device of this embodiment will be described. As described above, the dark current of LTPS has intense temperature characteristics. For this reason, in the display device shown in FIG. 4, measurement is performed using the photosensor on the light-shielding measurement side (second photosensor PS2) and the photosensor on the bright light measurement side (first photosensor PS1) separately. When calculating the bright current by calculating the output difference, the additional capacitor C may be varied in order to ensure the resolution. However, since the temperature change is large, the set width of the additional capacitor C must be increased. It is difficult to select the optimal capacity.

  Therefore, in the present embodiment, display control is realized by selecting the optimum additional capacitor C by the following method.

  First, the second photosensor PS2 on the light-shielding measurement side is measured with the same setting as during calibration, and a change in dark current can be measured by comparing with the value. In other words, since dark current is detected under a constant temperature environment during calibration, this is determined by comparing the dark current detection value of the second photosensor PS2 with the detection value during calibration. It can be converted into a temperature change.

  FIG. 7 is a diagram for explaining the flow of the display control method of the present embodiment based on this assumption. First, as initialization, a second photosensor is selected, and a comparator reference value and additional capacitance at the time of calibration are selected. Thereafter, the current at the time of light shielding is measured by the second photosensor (first measurement step).

  Next, as initialization, the second photosensor is selected, the comparator reference value is selected during calibration, and the ratio between the measurement result obtained by the second photosensor in the first step and the measurement result during calibration is calculated based on the darkness. The amount of current is estimated and an optimum capacity is selected, and then the current at the time of light shielding is again measured by the second photosensor (second measurement step).

  Next, as initialization, the first photosensor is selected, the comparator reference value at the time of calibration is selected, and the optimum capacity is selected, and then the peripheral light quantity is measured by the first photosensor (third measurement step). . Then, the illuminance is calculated from the measurement result by the following arithmetic expression.

Lout = L0 * SL * Sbk / (Sbk-SL) / Sc
here,
Lout: Output illuminance [lx]
Sbk: comparator output value [time (eg, step)] due to dark current when light is blocked by the second photosensor during calibration
SL: Comparator output value [time (for example, step)] by current when a constant illuminance L0 [lx] is applied by the first photosensor during calibration

Also, Sc in the above formula is as follows.
Sc = St × SRTbk / (Stbk−St)
here,
St: Comparator output value [time (for example, step)] based on the current value of the first photosensor when light is applied in actual measurement
Stbk: comparator output value [time (for example, step)] based on the current value of the second photosensor when light is shielded in actual measurement
SRTbk: Comparator output value [time (for example, step)] based on the current value of the second photosensor during light shielding when actual measurement is performed with the same additional capacitance as that at the time of calibration.

  And the said 1st measurement step-3rd measurement step is made into 1 cycle, and an illumination intensity is continuously calculated by the said computing equation. This makes it possible to obtain accurate illuminance while avoiding a decrease in resolution due to temperature and illuminance of external light.

  In the display device of the present embodiment, the backlight controller controls the amount of light emitted to the display area 11 (see FIG. 1) using the illuminance obtained in the above embodiment. For example, the light intensity of the backlight is increased as the obtained illuminance is brighter, and the backlight light quantity is adjusted to be smaller as the obtained illuminance is darker.

  The illuminance calculation and the backlight light amount control according to the present embodiment may be performed independently of the timing of displaying an image in the display area 11, but in order not to adversely affect the image display, It is desirable to perform certain processing in accordance with the timing of image display so that the display drive itself does not affect the sensor and from the viewpoint of easy system configuration.

  FIG. 8 is a diagram showing the timing of image display in the display area and detection by the photosensor. The image display in the display area is repeated with the vertical blanking period and the display period as one field. In the example shown in FIG. 8, four photosensors are provided, and each photosensor repeatedly executes the first measurement step to the third measurement step described above. One cycle of the first measurement step to the third measurement step is indicated by a broken line frame in the figure. At this time, initialization in each step is performed in a vertical blanking period in image display. Thereby, it is possible to prevent the sensor from being adversely affected by the content of the display image and the display drive itself so as not to affect the image display.

  In each photosensor, the length of the detection period (active) varies depending on the amount of light. This is because there is a difference in the comparator output value depending on the amount of received light.

  FIG. 9 is a diagram for explaining the operation timing in the initialization period. As described above, each photosensor performs initialization in each measurement step within the vertical blanking period of image display. That is, the initialization includes resetting the memory of the differential operation circuit and inputting various data. The input data includes information on which one of the first photodiode and the second photosensor is selected, information on the comparator reference value to be selected, and information on the additional capacitor to be selected.

  And the light quantity (illuminance) of the external light of a display area is calculated using the value detected by each photosensor, and the backlight controller shown in FIG. 1 controls the light quantity of a backlight based on this light quantity (illuminance). Become.

<Electronic equipment>
The display device according to the present embodiment includes a flat module-shaped display as shown in FIG. For example, on an insulating substrate, a pixel array part in which pixels made up of liquid crystal elements, thin film transistors, thin film capacitors, light receiving elements, etc. are integrated and formed in a matrix is provided, and an adhesive is provided so as to surround this pixel array part (pixel matrix part) And a counter substrate such as glass is attached to form a display module. If necessary, this transparent counter substrate may be provided with a color filter, a protective film, a light shielding film, and the like. For example, an FPC (flexible printed circuit) may be provided in the display module as a connector for inputting / outputting a signal to / from the pixel array unit from the outside.

  The display device according to the present embodiment described above is input to various electronic devices shown in FIGS. 11 to 15 such as a digital camera, a notebook personal computer, a mobile terminal device such as a mobile phone, and a video camera. The video signal generated or the video signal generated in the electronic device can be applied to a display device of an electronic device in any field for displaying as an image or a video. Below, an example of the electronic device to which this embodiment is applied is demonstrated.

  FIG. 11 is a perspective view showing a television to which the present embodiment is applied. The television according to this application example includes a video display screen unit 110 including a front panel 120, a filter glass 130, and the like, and is created by using the display device according to the present embodiment as the video display screen unit 110.

  12A and 12B are perspective views showing a digital camera to which the present embodiment is applied, in which FIG. 12A is a perspective view seen from the front side, and FIG. 12B is a perspective view seen from the back side. The digital camera according to this application example includes a light emitting unit 111 for flash, a display unit 112, a menu switch 113, a shutter button 114, and the like, and is manufactured by using the display device according to the present embodiment as the display unit 112. .

  FIG. 13 is a perspective view showing a notebook personal computer to which the present embodiment is applied. A notebook personal computer according to this application example includes a main body 121 including a keyboard 122 that is operated when characters or the like are input, a display unit 123 that displays an image, and the like, and the display unit 123 includes a display device according to the present embodiment. It is produced by using.

  FIG. 14 is a perspective view showing a video camera to which the present embodiment is applied. The video camera according to this application example includes a main body 131, a subject shooting lens 132 on a side facing forward, a start / stop switch 133 at the time of shooting, a display unit 134, and the like. It is manufactured by using the display device according to the above.

  FIG. 15 is a diagram showing a mobile terminal device to which the present embodiment is applied, for example, a mobile phone, in which (A) is a front view in an opened state, (B) is a side view thereof, and (C) is closed. (D) is a left side view, (E) is a right side view, (F) is a top view, and (G) is a bottom view. The mobile phone according to this application example includes an upper housing 141, a lower housing 142, a connecting portion (here, a hinge portion) 143, a display 144, a sub display 145, a picture light 146, a camera 147, and the like. In addition, the display device according to this embodiment is used as the sub display 145.

<Display imaging device>
The display device according to the present embodiment is applicable to the following display imaging device. In addition, the display imaging device can be applied to the various electronic devices described above. FIG. 16 illustrates the overall configuration of the display imaging apparatus. The display imaging apparatus includes an I / O display panel 2000, a backlight 1500, a display drive circuit 1200, a light receiving drive circuit 1300, an image processing unit 1400, and an application program execution unit 1100.

  The I / O display panel 2000 is composed of a liquid crystal panel (LCD (Liquid Crystal Display)) in which a plurality of pixels are arranged in a matrix over the entire surface, and a predetermined figure or character based on display data while performing line sequential operation. As well as a function (imaging function) for imaging an object that is in contact with or close to the I / O display 2000 as will be described later. The backlight 1500 is a light source of the I / O display panel 2000 in which, for example, a plurality of light emitting diodes are arranged, and at a high speed at a predetermined timing synchronized with the operation timing of the I / O display 2000 as described later. An on / off operation is performed.

  The display drive circuit 1200 drives the I / O display panel 2000 (drives line-sequential operation) so that an image based on display data is displayed on the I / O display panel 2000 (so as to perform a display operation). Circuit).

  The light receiving drive circuit 1300 is a circuit that drives the I / O display panel 2000 (drives line-sequential operation) so that light reception data can be obtained in the I / O display panel 2000 (so as to image an object). It is. The light reception data at each pixel is accumulated in the frame memory 1300A, for example, in units of frames, and is output to the image processing unit 14 as a captured image.

  The image processing unit 1400 performs predetermined image processing (arithmetic processing) based on the captured image output from the light receiving drive circuit 1300, and information (position coordinate data, object of the object) that is in contact with or close to the I / O display 2000. Data on the shape and size, etc.) are detected and acquired. The details of the detection process will be described later.

  The application program execution unit 1100 executes processing according to predetermined application software based on the detection result of the image processing unit 1400. For example, the display data includes the position coordinates of the detected object, and the I / O What is displayed on the display panel 2000 is mentioned. The display data generated by the application program execution unit 1100 is supplied to the display drive circuit 1200.

  Next, a detailed configuration example of the I / O display panel 2000 will be described with reference to FIG. The I / O display panel 2000 includes a display area (sensor area) 2100, a display H driver 2200, a display V driver 2300, a sensor readout H driver 2500, and a sensor V driver 2400. Yes.

  A display area (sensor area) 2100 is a region that modulates light from the backlight 1500 to emit display light and images an object that is in contact with or close to this area, and is a light emitting element (display element). And light receiving elements (imaging elements) described later are arranged in a matrix.

  The display H driver 2200 line-sequentially drives the liquid crystal elements of each pixel in the display area 2100 together with the display V driver 2300 based on the display drive display signal and the control clock supplied from the display drive circuit 1200. It is.

  The sensor readout H driver 2500 drives the light receiving element of each pixel in the sensor area 2100 together with the sensor V driver 2400 to obtain a light reception signal.

  Next, a detailed configuration example of each pixel in the display area 2100 will be described with reference to FIG. A pixel 3100 shown in FIG. 18 includes a liquid crystal element as a display element and a light receiving element.

  Specifically, on the display element side, a switching element 3100a made of a thin film transistor (TFT) or the like is disposed at the intersection of a gate electrode 3100h extending in the horizontal direction and a drain electrode 3100i extending in the vertical direction. A pixel electrode 3100b including liquid crystal is disposed between the switching element 3100a and the counter electrode. Then, the switching element 3100a is turned on / off based on a drive signal supplied via the gate electrode 3100h, and the pixel voltage is applied to the pixel electrode 3100b based on a display signal supplied via the drain electrode 3100i in the on state. Is applied and the display state is set.

  On the other hand, on the side of the light receiving element adjacent to the display element, a light receiving sensor 3100c made of, for example, a photodiode or the like is disposed, and the power supply voltage VDD is supplied. Further, a reset switch 3100d and a capacitor 3100e are connected to the light receiving sensor 3100c, and charges corresponding to the amount of received light are accumulated in the capacitor 3100e while being reset by the reset switch 3100d. The accumulated charge is supplied to the signal output electrode 3100j via the buffer amplifier 3100f at the timing when the readout switch 3100g is turned on, and is output to the outside. The on / off operation of the reset switch 3100d is controlled by a signal supplied from the reset electrode 3100k, and the on / off operation of the readout switch 3100g is controlled by a signal supplied from the readout control electrode 3100k.

  Next, a connection relationship between each pixel in the display area 2100 and the sensor readout H driver 2500 will be described with reference to FIG. In this display area 2100, a red (R) pixel 3100, a green (G) pixel 3200, and a blue (B) pixel 3300 are arranged side by side.

  The charges accumulated in the capacitors connected to the light receiving sensors 3100c, 3200c, and 3300c of each pixel are amplified by the respective buffer amplifiers 3100f, 3200f, and 3300f, and the signals are output at the timing when the readout switches 3100g, 3200g, and 3300g are turned on. It is supplied to the sensor reading H driver 2500 via the output electrode. Each signal output electrode is connected to a constant current source 4100a, 4100b, 4100c, and a signal corresponding to the amount of received light is detected with high sensitivity by the sensor reading H driver 2500.

  Next, the operation of the display imaging device will be described in detail.

  First, a basic operation of the display imaging apparatus, that is, an image display operation and an object imaging operation will be described.

  In this display imaging device, a display drive circuit 1200 generates a display drive signal based on display data supplied from the application program execution unit 1100, and the drive signal generates a line for the I / O display 2000. Sequential display drive is performed to display an image. At this time, the backlight 1500 is also driven by the display drive circuit 1200, and is turned on / off in synchronization with the I / O display 2000.

  Here, the relationship between the on / off state of the backlight 1500 and the display state of the I / O display panel 2000 will be described with reference to FIG.

  First, for example, when an image is displayed with a frame period of 1/60 seconds, the backlight 1500 is turned off (turned off) in the first half of each frame period (1/120 seconds), and display is not performed. On the other hand, in the second half of each frame period, the backlight 1500 is turned on (turned on), a display signal is supplied to each pixel, and an image in that frame period is displayed.

  Thus, the first half period of each frame period is a non-light period in which display light is not emitted from the I / O display panel 2000, while the display light is emitted from the I / O display panel 2000 in the second half period of each frame period. It has become a light period.

  Here, when there is an object (for example, a fingertip) in contact with or close to the I / O display panel 2000, the light receiving element of each pixel in the I / O display panel 2000 is driven by line sequential light receiving driving by the light receiving drive circuit 1300. The object is imaged, and a light receiving signal from each light receiving element is supplied to the light receiving drive circuit 1300. In the light receiving drive circuit 1300, the light receiving signals of the pixels for one frame are accumulated and output to the image processing unit 14 as a captured image.

  The image processing unit 1400 performs predetermined image processing (arithmetic processing) described below based on the captured image, and information (position coordinate data, object shape, and the like) related to an object in contact with or close to the I / O display 2000. Size data) is detected.

  DESCRIPTION OF SYMBOLS 10 ... Display panel, 11 ... Display area, 12 ... Selection switch, 13 ... V driver, 14 ... Display driver, 15 ... Sensor driver, 102 ... Comparator, 104 ... Difference calculating circuit, PS ... Photo sensor, PS1 ... 1st Photosensor, PS2 ... second photosensor, SW1 ... changeover switch, SW2 ... changeover switch

Claims (3)

A first detection element that outputs a current corresponding to the amount of external light ;
A first reset switch that sets an output of the first detection element to a predetermined potential before starting detection of external light;
A second detection element that outputs a current corresponding to a dark current when the external light is shielded ,
A second reset switch for setting the output of the second detection element to a predetermined potential before starting detection of light shielding;
A selection means for selecting one of the first detection element and the second detection element;
An output line common to the first detection element and the second detection element and the selection means are connected to each other and output from the first detection element or the second detection element selected by the selection means An additional capacitance element that is charged by a current that is applied ;
Comparing the voltage value and the first reference voltage value of the additional capacitor is charged by current output from the first detecting element when it is selected the first detection element by a pre-Symbol selection means, A comparator that compares a voltage value of the additional capacitance element charged by a current output from the second detection element with a second reference voltage value when the second detection element is selected by the selection unit. When,
When the first detection element is selected by the selection means, the time until the voltage of the additional capacitance element exceeds the first reference voltage value after the first detection element is set to a predetermined potential is shown. A first count value is obtained, and when the second detection element is selected, the voltage of the additional capacitance element exceeds the second reference voltage value after the second detection element is set to a predetermined potential. A control means for obtaining a second count value indicating time, calculating a difference between the first count value and the second count value, and controlling the amount of light applied to the display area according to the calculation result;
The first reference voltage value stored in advance in the memory when the selection unit selects the first detection element according to the performance variation of the first detection element and the second detection element. And a reference voltage value switching means for setting a second reference voltage value stored in the memory in advance when the second detection element is selected by the selection means,
Before Symbol first reference voltage value and the second reference voltage value, in a state in which the additional capacitor of said additional capacitance element is fixed, and the first count value upon detection of dark current by the first detection element The display device is adjusted so that the second count value when the dark current is detected by the second detection element matches. A display control method for a display device, comprising: a first detection element that outputs a current corresponding to the amount of external light; and a second detection element that outputs a current corresponding to a dark current when the external light is blocked. Yes,
Before starting the detection of outside light, setting the output of the first detection element to a predetermined potential with a first reset switch;
Setting the output of the second detection element to a predetermined potential with a second reset switch before starting detection of light shielding;
The first detection element is selected by a comparator that selects one of the first detection element and the second detection element and is connected in common to the first detection element and the second detection element. Is selected, the voltage value of the additional capacitance element charged by the current output from the first detection element is compared with the first reference voltage value, and the first detection element is set to a predetermined potential. Obtaining a first count value indicating a time until the voltage of the additional capacitive element exceeds the first reference voltage value after being set ;
When the second detection element is selected, a voltage value of the additional capacitance element charged by a current output from the second detection element is compared with a second reference voltage value, and the second reference voltage value is compared. Obtaining a second count value indicating a time until the voltage of the additional capacitance element exceeds a second reference voltage value after the detection element is set to a predetermined potential ;
Calculates the difference between the second count value and the first count value, and controlling the amount of light given to the display area depending on the calculation result,
When the first detection element is selected according to the performance variation of the first detection element and the second detection element, the first reference voltage value stored in the memory is set in advance. A step of switching to set a second reference voltage value stored in advance in the memory when the second detection element is selected by the selection unit , and
The first reference voltage value and the second reference voltage value are the first count value when a dark current is detected by the first detection element in a state where the additional capacitance of the additional capacitance element is fixed, and A display control method in which the second count value when dark current is detected by the second detection element is adjusted to coincide with the second count value . An electronic device provided with a display device in a housing,
The display device
A first detection element that outputs a current corresponding to the amount of external light ;
A first reset switch that sets an output of the first detection element to a predetermined potential before starting detection of external light;
A second detection element that outputs a current corresponding to a dark current when the external light is shielded ,
A second reset switch for setting the output of the second detection element to a predetermined potential before starting detection of light shielding;
A selection means for selecting one of the first detection element and the second detection element;
An output line common to the first detection element and the second detection element and the selection means are connected to each other and output from the first detection element or the second detection element selected by the selection means An additional capacitance element that is charged by a current that is applied ;
Comparing the voltage value and the first reference voltage value of the additional capacitor is charged by current output from the first detecting element when it is selected the first detection element by a pre-Symbol selection means, A comparator that compares a voltage value of the additional capacitance element charged by a current output from the second detection element with a second reference voltage value when the second detection element is selected by the selection unit. When,
When the first detection element is selected by the selection means, the time until the voltage of the additional capacitance element exceeds the first reference voltage value after the first detection element is set to a predetermined potential is shown. A first count value is obtained, and when the second detection element is selected, the voltage of the additional capacitance element exceeds the second reference voltage value after the second detection element is set to a predetermined potential. A control means for obtaining a second count value indicating time, calculating a difference between the first count value and the second count value, and controlling the amount of light applied to the display area according to the calculation result;
The first reference voltage value stored in advance in the memory when the selection unit selects the first detection element according to the performance variation of the first detection element and the second detection element. And a reference voltage value switching means for setting a second reference voltage value stored in the memory in advance when the second detection element is selected by the selection means,
Before Symbol first reference voltage value and the second reference voltage value, in a state in which the additional capacitor of said additional capacitance element is fixed, and the first count value upon detection of dark current by the first detection element The electronic device is adjusted so that the second count value when the dark current is detected by the second detection element coincides with the second count value .

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